/*
 * Copyright (c) 2010, 2014, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package org.openjdk.btrace.runtime.profiling;


import org.openjdk.btrace.core.Profiler;

import java.lang.ref.WeakReference;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentLinkedDeque;

/**
 * Implementation of {@linkplain Profiler}
 *
 * @author Jaroslav Bachorik
 */
public class MethodInvocationProfiler extends Profiler implements Profiler.MBeanValueProvider {

    private final Collection<WeakReference<MethodInvocationRecorder>> recorders = new ConcurrentLinkedDeque<>();
    private final int expectedBlockCnt;
    private final ThreadLocal<MethodInvocationRecorder> recorder = new ThreadLocal<MethodInvocationRecorder>() {
        @Override
        protected MethodInvocationRecorder initialValue() {
            MethodInvocationRecorder mir = new MethodInvocationRecorder(expectedBlockCnt);
            recorders.add(new WeakReference<>(mir));
            return mir;
        }
    };
    private volatile Snapshot lastValidSnapshot = null;
    private long lastTs = START_TIME;

    public MethodInvocationProfiler(int expectedMethodCnt) {
        expectedBlockCnt = expectedMethodCnt;
    }

    @Override
    public void recordEntry(String blockName) {
        recorder.get().recordEntry(blockName);
    }

    @Override
    public void recordExit(String blockName, long duration) {
        recorder.get().recordExit(blockName, duration);
    }

    @Override
    public void reset() {
        for (WeakReference<MethodInvocationRecorder> mirRef : recorders) {
            MethodInvocationRecorder mir = mirRef.get();
            if (mir != null) {
                mir.reset();
            }
        }
    }

    @Override
    public Snapshot snapshot(boolean reset) {
        Map<String, Integer> idMap = new HashMap<>();

        Record[] mergedRecords = null;
        int mergedEntries = 0, mergedCapacity = 0;
        for (WeakReference<MethodInvocationRecorder> mirRef : recorders) {
            MethodInvocationRecorder mir = mirRef.get();
            if (mir == null) continue;

            Record[] records = mir.getRecords(reset);
            if (records == null || records.length == 0) continue; // just skip the empty data

            if (mergedRecords == null) {
                mergedRecords = records;
                mergedCapacity = mergedRecords.length;
                for (int i = 0; i < records.length; i++) {
                    if (records[i] != null) {
                        mergedEntries = i + 1;
                        idMap.put(records[i].blockName, i);
                    }
                }
                continue;
            }

            for (Record r : records) {
                Integer id = idMap.get(r.blockName);
                if (id == null) {
                    id = mergedEntries++;
                    if (mergedEntries > mergedCapacity) {
                        mergedCapacity = (((mergedEntries + 1) * 5) >> 2);
                        Record[] newRecs = new Record[mergedCapacity];
                        System.arraycopy(mergedRecords, 0, newRecs, 0, mergedEntries - 1);
                        mergedRecords = newRecs;
                    }
                    idMap.put(r.blockName, id);
                    mergedRecords[id] = r;
                } else {
                    Record merged = mergedRecords[id];
                    merged.invocations += r.invocations;
                    merged.selfTime += r.selfTime;
                    merged.wallTime += r.wallTime;
                }
            }
        }
        Record[] rslt = new Record[mergedEntries];
        if (mergedRecords != null) {
            System.arraycopy(mergedRecords, 0, rslt, 0, mergedEntries);
        }

        long curTs = System.currentTimeMillis();
        Snapshot snp = new Snapshot(rslt, lastTs, curTs);
        lastTs = curTs;
        lastValidSnapshot = snp;
        return snp;
    }

    @Override
    public Snapshot getMBeanValue() {
        return lastValidSnapshot;
    }
}
